Fogel R, Mashazi P, Nyokong T, Limson J
Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, Grahamstown, South Africa.
Biosens Bioelectron. 2007 Aug 30;23(1):95-101. doi: 10.1016/j.bios.2007.03.012. Epub 2007 Mar 25.
One of the challenges in electrochemical biosensor design is gaining a fundamental knowledge of the processes underlying immobilisation of the molecules onto the electrode surface. This is of particular importance in biocomposite sensors where concerns have arisen as to the nature of the interaction between the biological and synthetic molecules immobilised. We examined the use of the Quartz Crystal Microbalance with Dissipation (QCM-D) as a tool for fundamental analyses of a model sensor constructed by the immobilisation of cobalt(II) phthalocyanine (TCACoPc) and glucose oxidase (GOx) onto a gold-quartz electrode (electrode surface) for the enhanced detection of glucose. The model sensor was constructed in aqueous phase and covalently linked the gold surface to the TCACoPc, and the TCACoPc to the GOx, using the QCM-D. The aqueous metallophthalocyanine (MPc) formed a multi-layer over the surface of the electrode, which could be removed to leave a monolayer with a mass loading that compared favourably to the theoretical value expected. Analysis of frequency and dissipation plots indicated covalent attachment of glucose oxidase onto the metallophthalocyanine layer. The amount of GOx bound using the model system compared favourably to calculations derived from the maximal amperometric functioning of the electrochemical sensor (examined in previously-published literature, Mashazi, P.N., Ozoemena, K.I., Nyokong, T., 2006. Electrochim. Acta 52, 177-186), but not to theoretical values derived from dimensions of GOx as established by crystallography. The strength of the binding of the GOx film with the TCACoPc layer was tested by using 2% SDS as a denaturant/surfactant, and the GOx film was not found to be significantly affected by exposure to this. This paper thus showed that QCM-D can be used in order to model essential processes and interactions that dictate the functional parameters of a biosensor.
电化学生物传感器设计面临的挑战之一是要深入了解分子固定在电极表面的基本过程。这在生物复合传感器中尤为重要，因为人们对固定的生物分子与合成分子之间相互作用的性质存在担忧。我们研究了使用耗散型石英晶体微天平（QCM-D）作为一种工具，对通过将钴（II）酞菁（TCACoPc）和葡萄糖氧化酶（GOx）固定在金-石英电极（电极表面）上构建的模型传感器进行基础分析，以增强对葡萄糖的检测。该模型传感器在水相中构建，使用QCM-D将金表面与TCACoPc共价连接，再将TCACoPc与GOx共价连接。水基金属酞菁（MPc）在电极表面形成多层结构，该多层结构可以去除，从而留下单层结构，其质量负载与预期的理论值相当。频率和耗散图分析表明葡萄糖氧化酶共价附着在金属酞菁层上。使用该模型系统结合的GOx量与从电化学传感器的最大安培功能推导的计算结果相当（见先前发表的文献，Mashazi, P.N., Ozoemena, K.I., Nyokong, T., 2006. Electrochim. Acta 52, 177 - 186），但与通过晶体学确定的GOx尺寸推导的理论值不同。通过使用2% SDS作为变性剂/表面活性剂测试了GOx膜与TCACoPc层的结合强度，发现GOx膜在暴露于该物质时未受到显著影响。因此，本文表明QCM-D可用于模拟决定生物传感器功能参数的基本过程和相互作用。
